The financial director of NCB Stockbrokers has said he only discovered during a TV interview last year involving the Taoiseach that money intended for Bertie Ahern's constituency office was a personal donation.
Graham O'Brien has been giving evidence to the Mahon Tribunal, which is investigating payments to Mr Ahern.
Mr O'Brien was NCB's financial controller in 1993 when the £5,000 punt payment was made and said he understood the money was a political donation.
Mr O'Brien has confirmed that he and the then financial director and chief executive Padraic O'Connor were all aware the money was paid on foot of a bogus invoice.
He has told the tribunal that neither he nor Chris McHugh were happy about the invoice but "that was the way Mr O'Connor wanted to do it".
The money ended up being paid by the former Fianna Fáil chief fundraiser Des Richardson into Bertie Ahern's personal account.